SINKING FUND: IN GENERAL.

(a) A resolution or order authorizing the issuance of obligations under this chapter must provide for the creation of a sinking fund. Amounts sufficient to pay the principal of and interest on the obligations shall be paid into the fund from the revenue pledged to the payment of the obligations. The payments into the fund shall be made monthly as the revenue is collected.

(b) In the manner provided by this chapter, the money in the sinking fund shall be applied, at or before maturity of the obligations, solely to:

(1) the payment of interest on the obligations for the payment of which the fund is created; and

(2) the retirement of the obligations.

(c) A resolution or order authorizing the issuance of obligations under this chapter must provide that the revenue from which the obligations are to be paid and that is pledged to the payment of the obligations shall be:

(1) set apart and paid into the sinking fund monthly as the revenue accrues and is received; and

(2) disbursed in the manner provided by this chapter.

(d) In determining the amount of revenue to be set apart, the board shall provide that the amount to be set apart and paid into the sinking fund in any year shall be not less than a fixed amount. The fixed amount must be at least sufficient to:

(1) provide for the payment of the principal of and interest on all obligations maturing and becoming payable in the year; and

(2) create a surplus or margin of 10 percent in excess of the amount needed under Subdivision (1).